Taurine is the most abundant free amino acid in the human body, found in high concentrations in the brain, retina, heart, skeletal muscle, and immune cells. Unlike most amino acids, taurine is not incorporated into proteins. It acts as an osmolyte, membrane stabilizer, calcium modulator, bile acid conjugate, and antioxidant. You get taurine from meat, fish, and dairy, and your body synthesizes small amounts from cysteine.

The Science paper by Singh et al. (2023) began with a simple measurement: blood taurine across age groups. In mice, taurine declined more than 80% between youth and old age. In rhesus macaques, about 85%. In humans, more than 80% between ages 5 and 60. The decline was consistent across species, sexes, and populations.

To test causality, Yadav's team supplemented taurine across species. In mice, 1,000 mg/kg/day in drinking water, started at 14 months (roughly 45 human years), extended median lifespan by 10% in females and 12% in males. Treated mice showed increased bone density by 7%, improved muscle endurance by 20%, reduced body fat, improved glucose tolerance, decreased inflammation, and improved memory.

At the cellular level, taurine-supplemented mice showed reduced DNA damage, lower p16INK4a senescence markers, improved mitochondrial complex I and IV activity, decreased telomere attrition, and reduced endoplasmic reticulum stress. The authors found taurine deficiency contributed to at least eight of the twelve recognized hallmarks of aging.

In rhesus macaques, six months of taurine supplementation improved body weight control, bone density at lumbar spine and femur, fasting glucose, and immune function. The primate data is important because primates share taurine metabolism pathways with humans in ways rodents do not.

A cross-sectional analysis of approximately 12,000 adults from the EPIC-Norfolk cohort showed that higher serum taurine was associated with lower BMI, lower fasting glucose, lower triglycerides, lower blood pressure, and lower hs-CRP, even after adjusting for confounders.

The mechanism involves taurine's role in mitochondrial protein synthesis. Taurine is required for post-transcriptional modification of mitochondrial tRNAs at the wobble position. Without adequate taurine, mitochondrial protein synthesis is impaired, electron transport chain complexes are misassembled, and ATP production drops. This is a substrate deficiency that progressively worsens as taurine levels decline.

Taurine supplements are widely available and inexpensive ($10–$20/month for 1,000–2,000 mg/day). Clinical studies have used doses up to 6,000 mg/day without significant adverse effects. The NIA's Interventions Testing Program has added taurine to its pipeline, with results expected by 2027. The biological rationale is strong, the cost is negligible, and the safety profile spans decades of human use.